It is known that micro-mechanical springs for suspending seismic masses in rotation rate sensors to a certain extent already cause deflections in the reading-out direction in the drive mode or primary mode owing to relatively small fabrication inaccuracies which lead, in particular, to undesired edge angles of the respective structures without the presence of a rotation rate. As a result, interference signals are generated which can be undesirably evaluated as rotation rate signal components and therefore falsify the rotation rate signal or cause a measuring error with respect to the rotation rate signal.
Such undesired edge angles or tilting of springs are process-induced and can be avoided only to a limited degree. The interference signals described above, which do not come about owing to a detected rotation rate but rather owing to faulty deflections in the reading-out direction as a function of the deflection of the seismic mass and the springs thereof in the drive direction, are also referred to as quadrature or quadrature signals.
Document WO 03/010492 A1, which is incorporated by reference, proposes a method for suppressing quadrature signals in a rotation rate sensor which comprises two trimming electrode arrangements which are associated with a seismic mass, in which method the quadrature of the rotation rate sensor is suppressed by means of the voltage applied to the trimming electrodes. However, this quadrature suppression can undesirably influence the resonance frequency of the reading-out mode of the rotation rate sensor, as a result of which the differential frequency between the resonance frequencies is also changed with respect to the drive mode or primary mode and the reading-out mode or secondary mode of the rotation rate sensor. This is all the more disadvantageous since the voltage which is applied to the trimming electrodes is included quadratically in the shifting of the resonance frequency of the reading-out mode.
It is customary that the embodiment of the quadrature of rotation rate sensors of a wafer varies to a relatively high degree owing to process fluctuations and differs to a relatively high degree from one rotation rate sensor to another of a wafer.
Furthermore, it is known to reset the deflection of the seismic mass/masses of a rotation rate sensor with respect to the reading-out mode or secondary mode by means of at least one trimming electrode element or a trimming electrode. However, this also usually influences the resonance frequency of the secondary oscillator, as well as influencing possible quadrature suppression.